title: Alterations in renal and hepatic nitrogen metabolism in rats during HCl ingestion.
abstract: The effect of prolonged metabolic acidosis on hepatic and renal enzymes associated with nitrogen metabolism was investigated. The rates of urinary ammonia and urea excretion were also determined. Administration of 9 mmol HCl daily for 8 days resulted in severe metabolic acidosis. The activity of the first two enzymes of the urea cycle, carbamoyl phosphate synthetase (CPS) and ornithine transcarbamoylase (OTC), was 30% greater in chronically acidotic rats than in pair-fed controls. There was also a fivefold increase in renal phosphate-dependent glutaminase (PDG) activity and an 18 to 24-fold increase in renal ammonia excretion. Urea excretion was not constant in the acidotic group, decreasing during the first 4 days and gradually returning to pair-fed control levels between the fourth and eighth day. The return to control levels of urinary urea excretion coincided with the plateau of urinary ammonia excretion that occurred by day 4 in the acidotic group. A similar pattern of urea nitrogen excretion has been observed in both NH4Cl and HCl acidosis, ie, an initial decrease in urea excretion followed by a gradual increase with time. These results suggest that hepatic urea synthesis does not play a significant role in long-term regulation of the acid-base balance in rats during chronic metabolic acidosis.
authors.affiliation: Physiology Department, University College Galway, Ireland.
authors.forename: A L
authors.initials: AL
authors.lastname: Lardner
authors.forename: D J
authors.initials: DJ
authors.lastname: O'Donovan
mesh_terms: D000138:Acidosis / Q000378:metabolism*; D000818:Animals; D002222:Carbamoyl-Phosphate Synthase (Ammonia) / Q000378:metabolism; D005260:Female; D007668:Kidney / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*; D009954:Ornithine Carbamoyltransferase / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014508:Urea / Q000378:metabolism
chemical_list: D014508:Urea; D009954:Ornithine Carbamoyltransferase; D002222:Carbamoyl-Phosphate Synthase (Ammonia); D009584:Nitrogen